Abstract
Totally water-soluble N-doped Carbon dots (N-CDs) were synthesized by a green hydrothermal method from biomass using Highland barley as a carbon source and ethanediamine as nitrogen source. TEM and XRD showed the graphitic amorphous structure and narrow diameter distribution of these N-CDs. N-doping to the crystal lattice and carrying many hydrophilic groups on the surface of N-CDs were verified by XPS and FT-IR. The as-synthesized N-CDs emitted strong blue fluorescence at 480 nm and owned a relatively high quantum yield of 14.4%. The product also could sensitively and selectively detect Hg2+ ions in the range of 10–160 μM and the limit of detection was equal to 0.48 μM.
Highlights
Carbon dots (CDs) have attracted increasing attention due to their unique characteristics such as excellent optical and electronic properties, good water-solubility, low toxicity, and perfect biocompatibility [1,2,3,4,5,6] among others
nitrogen-doped CDs (N-CDs) can be derived in two main ways [15]: (1) employing small molecular precursors which possess higher nitrogen contents to synthesize N-CDs from bottom-up methods [16,17,18,19], as the obtained products usually have higher fluorescence quantum yield (QY) but involve a complicated process
When the dosage of Highland barley increased from 2 g to 4 g, the QY of CDs increased sharply and slightly reduced when the mass was greater than 4 g
Summary
Carbon dots (CDs) have attracted increasing attention due to their unique characteristics such as excellent optical and electronic properties, good water-solubility, low toxicity, and perfect biocompatibility [1,2,3,4,5,6] among others. N-CDs can be derived in two main ways [15]: (1) employing small molecular precursors which possess higher nitrogen contents to synthesize N-CDs from bottom-up methods [16,17,18,19], as the obtained products usually have higher fluorescence quantum yield (QY) but involve a complicated process. (2) Using natural biomass precursors which contain a carbon and nitrogen source together to prepare N-CDs by top-down methods. In an especially green economical hydrothermal treatment [20,21,22], these N-CDs often possess relatively low QY. Natural biomass materials are ubiquitous, nontoxic, cheap, and reproducible. They are still growing challengeable precursors in the preparation of N-CDs
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